Speaker
Description
Ground-level enhancements (GLE) designate eventS where relativistic protons and ions of solar origin trigger a cascade of secondary nucleons in the Earth’s atmosphere that can be detected on ground. GLEs require primary particles with energies of at least 430 MeV/nucleon, with a spectrum that may extend to several tens of GeV. They are extremes of solar particle acceleration, which pose challenging problems to candidate ac- celeration processes. The association with eruptive solar flares suggests processes related to magnetic reconnection in the flaring corona and shock waves driven by particularly fast coronal mass ejections. Pion-decay gamma-rays, which come from the interaction of nucleons with energies above 300 MeV/nucleon with the low solar atmosphere, have shown that relativistic proton acceleration is much more frequent than GLEs. In this talk I will review observational evidence on the acceleration process and discuss the pros and cons of the two categories invoked in the literature.
| Session | 1 - Cosmic Rays in the Heliosphere |
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